Manufacture of electrical fuses.



Patented Nov. I4, I899. n. m. HUNTER.

2 Sheets-Sheet MANUFACTURE OF ELECTRICAL FUSES.

(Application filed Nov. 11, 1896. Renewed May 1, 1899.) (No Model.)

I'lll No. 637,120. Patented Nov. I4, 1899'.

R. m. HUNTER.

MANUFACTURE OF ELECTRICAL FUSES.

(Application filed Nov. 11, 1896. Renewed May 1, 1899.) (No Model.) 2Sheets-Sheet 2.

FIG-.7.

knvenior "n-z: :wnms PETERS co. FHQYO-L|THO., WASHINGTON, o. c.

UNITED STATES PATENT OFFICE.

RUDOLPH M. HUNTER, OF PHILADELPHIA, PENNSYLVANIA.

MANUFACTURE OF ELECTRICAL FUSES.

SPECIFICATION forming part of Letters Patent No. 637,120, dated November14, 1899. Application filed November 11, 1896- Renewed May 1, 1899.Serial No. 715,205. (No model.)

To 'LtZZ whom it may concern:

Be it known that I, RUDOLPH M. HUNTER, of the city and county ofPhiladelphia and State of Pennsylvania, have invented an Improvement inthe Manufacture of Electrical Fuses, of which the following is aspecification:

My invention has reference to the manufacture of electrical fuses; andit consists of certain improvements, which are fully set forth in thefollowing specification and are shown in the accompanying drawings,which form a part thereof.

This application (Case No. 293) comprehends a certain method or processfor the manufacture of fuses for electrical circuits and the machines orapparatus therefor.

Heretofore electrical fuses or fuse-wires have been made of a suitablefusible alloy containing lead and tin, with or without other metals, andthe said alloy after being cast is rolled down to the requisitecross-section calculated to carry a given current in amperes withoutfusing, but adapted to melt or fuse upon an excess of current beyondsaid calculated amount being unintentionally caused to pass over thecircuit. In some cases the fuses are rolled out into flat plates, whichare sub sequently notched to reduce the width of the rolled plate at ornear the middle and have their ends united to stamped sheetmetal clamps,this latter construction being the form commonly employed on largecircuits. Large quantities of the smaller fuses are formed of shortlengths of the rolled-alloy wire and the ends united by soldering tostamped slotted copper clamping terminals. This method of constructingfuses is not only expensive, but is unreliable, since it is impossibleto roll a soft alloy and secure a uniform density, without which noreliability can be had as to the current-carrying capacity from a givencross-section. This defect often permits the passage of as high as fortyper cent. more current than its rated capacity. The same continuouslength of fuse-wire will vary in its current-carrying capacity almostwith every foot of its length, and hence the fuses made from the samereel cannot be relied upon for carrying only a definite current beforefusing. The difficulty ofdetecting these defects before actual use liesin the fact that to test the fuse means to destroy it beforeascertaining its capacity, and, furthermore; the testing of one fuse isno evidence that the next one of the same batch will respond to the sametest.

My invention is designed to overcome these defects in the fuses asheretofore made; and my object is to manufacture fuses in such a mannerthat every fuse will carry exactly the currentitis intended to carry andno more and all fuses of a given capacity will each have that capacityassured without test or experi-' ment.

In carrying out my invention I dispense entirely with rolling and castthe fuse in the predetermined shape under a given and uniform pressure.If a sufficient pressure he employed, blow-holes will be eliminated andthe density of the alloy must of necessity be uniform. When theseresults are secured, every fuse of a given cross-section will carryexactly the same current before fusing.

In carrying out my invention I may employ either of two methods or modesof operation. The preferred method is to feed automatically into amoving mold the fusible alloy under a given or constant pressure andpreferably secured by employinga column of molten alloy. Suitabledevices are employed to maintain that column constant or uniform inheight, so that irrespective of the amount of metal taken away in themold the upper level of the column of metal is constant. The manufactureof fuses by this method is only limited by the speed with which themetal may be molded. I prefer to employ a rotating mold-wheel having itsface formed with molds which are moved rapidly over a moldsection in theform of a curved casting, through an aperture in which the alloy is fedto the mold. As the mold-wheelsurface passes below the mold-section thefuses drop out of the molds by gravity.

Fuses formed as above may have the de sired shape and cross-section anddefinite current carrying capacity. I form. the fuses preferably of archform, with the smallest sectional area in the center of the crown tofacilitate the blowing at that point and also with slotted feet forclamping to the fuse blocks. To give good contact and durability in use,I subject the feet of the fuses so formed ICO to an electrolytic bath ofcopper and deposit electrically a coating of copper upon these partsofsufficientthiclmess toimpartstrength and reduce the resistance. Byplating these feet with a heavy layer of copper the soft fuse metal oralloy is incased in copper and cannot be squeezed out of shape veryreadily, thereby insuring a good electrical connection in the circuit.This secures all of the advantages of the solid stamped copperterminals, while avoiding their expense. Moreover, by casting my fuses Ican secure the desired cross-section at every part, so that thefusing-section is decidedly of the least resistance, thus insuring therupture or blowing occurring at a definite place.

My invention will be better understood by reference to the accompanyingdrawings, in which- Figure l is a sectional elevation of a machine forcarrying out my preferred process of making fuses. Fig. 2 is across-section of same on line :0 (c. Fig. 3 is a perspective View of oneof my improved fuses. Fig. 4 is a perspective view of a portion of themold- Wheel. Fig. 5 is aside elevation of one of my fuses. Fig. 6 is across-section of a portion of the mold, showing a modified crosssectionof the fuse-mold; and Fig. 7 is a sectional elevation of agalvanizing-bath.

A is the main frame of the machine and has jonrnaled in it near thebottom a transverse shaft C, upon which is secured the mold-wheel B. Theshaft 0 may be rotated by a worm and worm-wheel D and a bandwheel E orotherwise. The cross-section of the rim of the mold-wheel B is bestshown in Figs. 2 and 4, the same being with a higher central rim Bintermediate of the two lateral or flange surfaces B. The mold b isformed or cut into the outer surfaces of the rim of the mold-wheel, asclearly shown in Figs. 1, 2, and 4:. The rim of the mold-wheel moves incontact with a curved mold-section F, constituting the outer part of themold. This part F is stationary and carried by the main frame A in anysuitable manner. The part F has its upper portion formed with a metalchamber to receive the molten alloy and is furnished with acasting-aperture f, through which the fluid metal finds ready access tothe molds in the mold-wheel as they pass the aperture. The front of themetal-chamber may have a removable plug or stopper g to permit access tothe chamber for cleaning purposes and for allowing a portion of themetal to flow off at starting to insure all air being ejected from thefluid alloy. This latter precaution would hardly be necessary inpractice, because of the great weight of the column of metal under whichthe casting takes place.

The lower portion of the mold-section F acts as a curved guide-surfaceover which the castings are moved while cooling, and the solidifying maybe quickened by the employment of a water-jacket F, through which coldwater may be passed by pipes G. As the mold-wheel passes on in itsrevolution the castings are ultimately carried beyond the mold-sectionF, and thereby permitted to drop by gravity from the molds. The moldsare preferably formed with sufficient taper in all directions andflaring toward the outer surface of the mold-wheel to insure the readyliberation of the castings. This is furthermore increased by theshrinkage of the castings in hardening.

Fitted to the top of the chamber F in the mold-section F is the hollowcolumn, tube, or stand-pipe I, which may be of any height desired. Inpractice I prefer to make it about five feet, and upon the top of it Iarrange a metal-pot I. To one side of this pot I movably support orhinge at 'i a pan 1 adapted to contain a large quantity of molten alloyS. By tilting the pan 1 it is evident that the level of the alloy in thepot I may be raised or lowered or maintained at a definite level. Thispan or reservoir may be adjusted by any suitable means, that shown beingexcellently adapted to the purpose. This means consists of verticalscrew J, connected with the pan by a link and working through a rotatingnut having a worm-wheel J, which is driven by a worm and an electricmotor K. By making the pitch of the screw J and the worm small the partsare locked against running down, that latter action being secured onlyby reversing the electric motor in the usual way. The motor K is in anelectric circuit M, leading from a battery L or other source of electricenergy. A switch N opens or closes the motorcircuit M automatically andis controlled bya magnet O of high resistance in a circuit Q, alsoincluding the battery L, and put into or out of energized condition by acircuit-controlling switch operated by the fluid alloy. This latterswitch consists of a float 29, having a platinum contact and restingupon the molten metal in the pot I, and a contact-screw P,

carried by but insulated from the pot and making contact with thefloating contact 19. The circuit Q of the magnet 0 includes the parts Pand p of this controller or switch. The smallest variation in height ofthe level of the molten metal will break the contact between P and p,and thus open the circuit Q. and allow the armature-switch N to moveaway from the magnet under the action of a spring. This closes themotor-circuit and causes the motor K to rotate the worm-wheel and itsnut, with the result of raising the pan I slightly, and therefore thelevel of the metal. This result once more raises the float p and closesthe circuit 0, and thereby induces the opening of the motor-circuit. Byemploying speed-reducing gearing, such as shown between the motor K andscrew J, the motor may make a number of revolutions to raise the pan toa very small extent. Any

other automatic mechanism may be employed to maintain the fixed heightof the column of fluid alloyin lieu of that above described,

terially affect the fusing-point of the fuse.

It Will be essential to maintain the alloy in a fused or fluidcondition, and to do this I may employ a gas-jet H under the chamber Fwhere the alloy enters the mold, and a spiral burner H, arranged aroundthe stand pipe or tube I. A lateral burner-tube h may be ar ranged underthe pan I and moved with it.

* Any other means of supplying heat may be employed.

The preferred form offuse is shown in Figs. 3 and 5, and consists of thearched center T, having the smallest cross-section at t in the crown,and the slotted feet T at each end. The feet T of the fuse are suspendedin an electroplating-bath U, Fig. 7,' and coated with a layer of copper.A sufficient coating of the copper will completely confine the fusiblemetal at the feet and provide a perfect contact and also reduce theresistance. The hard copper envelop will confine the soft metal, andthus permit it to withstand the clamping action in the fuse-block. WhileI prefer this shape of fuse, it is to be understood that it may be madein any other shape.

In the general method as above set forth the fuse is cast of therequisite shape under a uniform pressure, and it is immaterial to myinvention, broadly considered, how this uniform pressure may be secured.The height of the column of alloy in Fig. 1 may be increased to vary thedensity of the casting in the same mold by adjusting the contact P togive to the given-sized fuse a different capacity; but in all cases themachines will make every fuse under like conditions and with the samecapacity once the machines are set to perform their work.

The details of construction may be modified in various Ways withoutdeparting from the principles of my invention. Hence I do not limitmyself to the details shown.

What I claim as new, and desire to secure by Letters Patent, is

1. In a machine for making electrical fuses, the combination of a mold,a pressure device for introducing into the mold a fusible alloy under apredetermined pressure, and an automatic pressure-regulating deviceconstructed and arranged to be actuated by said pressure device.

2. In a machine for making electricalfuses, the combination of a mold, apressure device for introducing into the mold a fusible alloy under apredetermined pressure consisting of a column of the fusible alloy, andan automatic pressure-regulating device constructed and arranged to beactuated by the varying levels of the surface of the column of alloyforming said pressure device.

3. In a machine for making electrical fuses, the combination of a mold,means for continuously supplying to the mold a fusible al- 10y under asubstantially predetermined pressure, and automatic pressure-regulatingdevices to increase the said pressure whenever the same falls below thepredetermined pressure.

4. In a machine for making electrical fuses, the combination of a mold,a stand-pipe for holding fusible alloy and feeding it to the mold underuniform pressure, an auxiliary reservoir or receptacle for containing anexcess of the fusible alloy, and means for moving the auxiliaryreservoir for transferring fusible alloy from the auxiliary reservoir orreceptacle to the stand-pipe.

5. In a machine for making electrical fuses, the combination of a mold,a stand-pipe for holding fusible alloy and feeding it to the mold underuniform pressure, an auxiliary reservoir or receptacle for containing anexcess of the fusible alloy, and automatic means under the control ofthe metal level in the stand-pipe for transferring in small quantitiesand at intervals fusible alloy from the auxiliary reservoir orreceptacle to the standp In a machine for making electrical fuses, thecombination of two or more molds, apressure device for introducing thealloy to the mold successively under a predetermined pressure, and meansfor automatically regulating and controlling the pressure arranged andconstructed to be actuated by said pressure device, whereby all of themolds are supplied with the fusible alloy bythe same pressure andregulating devices and all castings are of exactly the same density.

7. In a machine for making electrical fuses, the combination of a mold,a pressure device for introducing into the mold a fusible alloy under apredetermined pressure, an automatic pressure-regulating deviceconstructed and arranged to be actuated by said pressure device, areservoir or receptacle for containing an excess of the fusible alloy,and means for transferring fusible alloy from the reservoir orreceptacle to the pressure device, whereby the pressure device isconstantly supplied with the proper quantity of fusible alloy for thecasting operations.

8. In a fuse-making machine, the combination of a tubular column forfusible alloy, a moving mold adapted to receive fusible alloy from thelower part of the column, a separate reservoir of fusible alloy, meansfor transferring fusible alloy from the separate reservoir to thetubular column, and automatic controlling devices under the control ofthe fusible alloy in the tubular column for controlling the means fortransferring the fusible alloy from the separate reservoir to thetubular column.

9. In a fuse-making machine, the combination of a tubular column forcontaining fusible alloy, a moving mold adapted to receive fusible alloyfrom the lower part of the column, means for supplying fusible alloy tothe top of the column to compensate for that run off from the bottom,and automatic devices for controlling the supply of fusible alloy to thecolumn constructed and arranged to be operated by the height of thecolumn of alloy.

10. Inafuse-makingmachine,thecombination of an upright tube for feedingan alloy under pressure, a mold adapted to receive al- 10y from thebottom of the tube, a reservoir of molten alloy movably supported so asto change the level of the column of alloy formed by the tube, anelectric motor to move the reservoir, a switch to control the motor, anelectromagnetic device to control the switch to arrest the operation ofthe motor, and means controlled by the height of the column of moltenalloy to control the electromagnetic device, whereby the motor isautomatically operated to increase the level of the molten alloy uponany appreciable lowering of the column of alloy.

11. In a fuse-making machine,the combination of a rotating mold-wheelhaving its surface formed with m0lds,a mold-section against which themold-wheel operates and provided with a casting-aperture, a tubularcolumn or stand-pipe opening from the mold-section to secure a constantand uniform pressure, and a reservoir for molten alloy at the upper partof the column or stand-pipe having a movable bottom.

12. In a fuse-making machine,the combination of a rotating mold-wheelhaving its surface formed with molds,a mold-section against which themold-wheel operates and provided with a casting-aperture, a tubularcolumn or stand-pipe opening from the mold-section, a reservoir formolten alloy at the upper part of the column or stand-pipe, means toraise or lower the reservoir to adjust the level of the molten alloy inthe stand-pipe, and means to heat the column or stand-pipe andreservoir.

13. In afuse-making machine,the combination of a moving mold having itssurface formed with mold-recesses, a tubular column or stand-pipe ofmetal for supplying alloy to the mold under pressure, a reservoir formolten alloy to one side of the upper part of the column or stand-pipe,and a gas-pipe having a portion spirally encircling the metal stand-pipeto heat the column or stand-pipe and formed with a lateral branch toheat the reservoir.

14:. In a fuse-making machine the combination of a moving mold having acontinuous smooth surface throughout its length and having formed in itssurface a series of shallow depressions the walls of which are fixed andflaring outwardly for receiving molten alloy whereby the surfacesurrounding and intermediate of said depressions is continuous andadapted to act as a seal or valve to the alloy-supplying means with asmooth moldsection against which the moving mold travels to form a closejoint, means for supplying sci-.1526

intermediate of said mold and mold-section a fusible alloy underpressure, and automatic pressure-regulating devices constructed andarranged to be actuated by the alloy when varied as to its pressurewhereby it is fed under constant and uniform pressure to the movingmold.

15. In a fuse-making machine,the combination of mold-wheel having itscircumference formed with an annular raised center and provided withmolds formed into the metal of the center and extending down its sidesand upon the circular lateral surfaces of the periphery, with amold-section having internal curved surfaces corresponding in shape tothe surface of the mold-wheel, and means for supplying a fusible metalthrough the mold-section into the molds.

16. In a fuse-making machine,the combination of mold-wheel having itscircumference formed with an annular raised center and provided withmolds formed into the metal of the center and extending down its sidesand upon the circular lateral surfaces of the periphery, with amold-section having internal curved surfaces corresponding in shape tothe surface of the mold-wheel, means for supplying a fusible metalthrough the moldsection into the molds, and means for maintaining thepressure of the fusible metal when casting always the same.

17. In a fuse-making machine,the combination of mold-wheel having itscircumference formed with an annular raised center and provided withmolds formed into the metal of the center and extending down its sidesand upon the circular lateral surfaces of the periphery, with amold-section having internal curved surfaces corresponding in shape tothe surface of the mold-wheel, means for supplying a fusible metalthrough the moldsection into the molds, and means for cooling themold-section to solidify and cool the castings before being discharged.

18. In a fuse-making machine, a mold for a fuse consisting of a movablemold-piece having a continuous surface furnished with a raised portion Bintermediate of two side portions 13 formed with their longitudinalsurfaces parallel and in which said portions 13 B and the two uprightside walls between them are provided with transverse moldgrooves, astationary mold-section fitted to the grooved surface of the movablemoldpiece to close the grooves in the surface of the mold, means to movethe movable mold-piece of the mold relatively to the stationarymoldsection, and means to supply a fusible metal to the grooves of themold under pressure.

19. In a fuse-making machine, a mold for a fuse consisting of a movablemold-piece having a continuous surface furnished with a raised portion Bintermediate of two side portions B formed with their longitudinalsurfaces parallel and in which said portions B B and the two uprightside walls between them are provided with transverse mold IIO groovesand in which the side walls of the mold-grooves flare outward at allpoints so that the castings automatically drop out of the grooves bygravity, a stationary mold-section fitted to the grooved surface of themovable mold-piece to close the grooves in the surface of the mold,means to move the movable mold-piece of the mold relatively to thestationary mold-section, and means to supply a fusible metal to thegrooves of the mold under pressure.

20. In a fuse-making machine, the combination of a mold, a stand-pipe ortubular column for supplying fusible metal to the mold under pressure, ametal pot at the top of the stand-pipe or column, and amolten-metalreservoir hinged or flexibly connected to or relatively to the pot forsupplying it with molten metal.

21. In a fuse-making machine, the combi- A nation of a mold, astand-pipeor tubular column for supplying fusible metal to the mold underpressure, a metal-pot at the top of the stand-pipe or column, amolten-metal reservoir hinged or flexibly connected to or relatively tothe pot for supplying it with molten metal, and automatic devices underthe control of the fusible alloy in the stand-pipe for operating thereservoir to supply molten metal to the pot for maintaining the level ofthe molten metal therein uniform.

22. The combination of a mold, a metal stand-pipe for delivering moltenalloy to the mold under pressure, and a spirally-arranged gas-pipehavingburner-openin gs surrounding the stand-pipe for heating it.

23. The combination of a mold, means for supplying a fusible alloy tothe mold under pressure, an auxiliary reservoir or receptacle for thefusible alloy, and automatic devices controlled by the pressure-creatingmeans constructed and operating to transfer the fusible alloy from thereservoir to the means for supplying it to the mold under pressure.

24. The combination of a mold, means for supplying a fusible alloy tothe mold under continuous and uniform pressure, an auxiliary reservoiror receptacle for the fusible alloy, devices constructed and operatingto transfer the fusible alloy from the reservoir to the means forsupplying it to the mold to maintain it at the same level, and automaticmeans controlled by the level of the alloy to govern the action of thetransferring devices.

25. The combination of a mold, an alloypot, means for conveying thealloy from the pot to the mold, movable auxiliary reservoir or vesselfor holding an excess of fusible al- 10y, means to move the auxiliaryreservoir for transferring the fusible alloy from the reservoir to thepot, and means to heat both the pot and reservoir.

26. The combination of a mold, an alloypot, means for conveying thealloy from the pot to the mold, an auxiliary reservoir or vessel forholding an excess of fusible alloy, means constructed and controlled bythe movement of an arm or lever for transferring the fusible alloy fromthe reservoir to the pot, a float resting upon the alloy and rising andfalling with its change of level, an electric contact controlled by saidfloat, an electric circuit including said contact, and anelectromagnetic device in the electric circuit and controlled by thecontact to operate the arm or lever of the transferring means.

27. The combination of a mold, means for supplying a fusible alloy tothe mold under uniform pressure, an auxiliary reservoir for fusiblealloy, devices constructed and operating to transfer the fusible alloyfrom the reservoir to the means for supplying it to the mold, and meansoperated by the level of the fusible alloy to electrically control theoper ation of the devices for transferring the fusible alloy.

28. In a machine for casting the combina-- tion of a mold, a stand-pipefor holding fusi ble alloy and feeding it to the mold under uniformpressure, an auxiliary reservoir independent of the' stand-pipe adaptedto contain much alloy and sustain it independently of the alloy in thestand-pipe, and means controlled by the pressure-creating alloy in thestand-pipe for transferring said alloy from the reservoir to thestand-pipe in a gradual manner so that it shall become active increating a pressure in the stand-pipe and maintain said pressureconstant and uniform.

29. In a machine for casting the combination of a mold, a stand-pipe forholding fusible alloy and feeding it to the mold under uniform pressure,an auxiliary reservoir independent of the stand-pipe adapted to containmuch alloy and sustain it independently of the alloyin the stand-pipe,means for transferring said alloy from the reservoir to the stand-pipein a gradual manner so as to become activein creating a pressure in thestandpipe and maintain said pressure constant and uniform, andelectrically-controlled means governed by the level of the alloy in thestandpipe to control the transferring means.

In testimony of which invention I have hereunto set my hand.

R. M. HUNTER.

Witnesses:

J. W. KENWORTHY, R. M. KELLY.

